Fluorescent chromosome-specific DNA probes allow identification of a variety of chromosome abnormalities in interphase and mitotic cells including aneuploids and breakage/rearrangement events, opening a new area of genetic investigation known as "molecular cytogenetics". Whole chromosome probes and chromosome region-specific probes are available for human and mouse chromosomes, but few such probes are available for rat chromosomes of other laboratory species used in reproductive, developmental, and cancer studies. We propose to provide such probes for rat, rabbit and non-human primate chromosomes by chromosomal DNA microdissection and by making and screening bacterial artificial chromosome (BAC) libraries. Specifically, in Phase II we will develop chromosome-specific point probes for the rat, rabbit, and rhesus macaque, and whole chromosome paint probes for a subset of rabbit and rhesus chromosomes. The choice of whole chromosome paint probes for rabbit and rhesus will be determined by consultation with collaborators experienced in in vivo genetic toxicology and reproductive biology. In addition, we propose to develop sets of probes for rat and human which will be used for chromosome identification, without the need for Giemsa banding or other more difficult staining procedures.